The present invention relates generally to hydrogen storage materials and more particularly to metal hydride batteries and hydrogen powered fuel cells using a hydrogen storage material that can be microfabricated under ambient atmospheric conditions.
Metal hydride storage systems, coupled with fuel cells, are considered a viable power source for powering not only automobiles, but also smaller traditionally battery-powered devices, such as remote sensors and telemetry devices, as well as other electronic devices, such as laptop computers and cellular phones.
The performance of hydrogen storage devices depends on many factors. Among those is a good hydrogen storage material with the following properties: (a) high capacity for storing hydrogen; (b) a suitable and preferably selectable hydrogen equilibrium pressure range (operating pressure); (c) an operating pressure near or slightly above atmospheric pressure; (d) an activation pressure (the pressure of hydrogen gas needed to first introduce hydrogen into the hydride material) at or near atmospheric pressure; (e) superior catalytic properties, with the material remaining active for hydrogen sorption and desorption after exposure to air and humidity; (f) a high hydrogen diffusion rate; (g) cyclability of the material through a large number of sorption/desorption cycles; (h) low cost; and i) manufacturability without the need to protect the material from the ambient atmosphere and humidity.
Conventional nickel-metal hydride batteries typically employ as negative electrode a hydrogen-absorbing alloy. Hydrogen-absorbing alloy electrodes can be prepared from a paste made by adding a binding agent to a hydrogen-absorbing alloy powder and then applying the paste to a current collector composed of a conductive material, for example a metal.
The energy stored in a nickel-metal hydride battery depends on the hydrogen-absorbing alloy that is accessible to hydrogen and can reversible bond to and eject hydrogen. The hydrogen-absorbing alloy that is accessible to hydrogen is proportional to the surface area of the exposed metal.
For small scale power delivery, the ability to fabricate the metal hydride hydrogen storage power source by standard microfabrication techniques, and more particularly under ambient conditions, such as room air humidity, would lower cost and expand the potential uses for fuel cells and hydrogen powered batteries.